In the art of vapor compression type heating, ventilating and air conditioning (HVAC) equipment, there has been a continuing need to provide a suitable expansion device which may be reliably controlled to minimize the chance of damage to the system compressor resulting from liquid working fluid entering the compressor, maintain the ability during steady state operation to adjust working fluid flow to meet system requirements and to otherwise protect the compressor from damage during system shutdown or during periods of continuous low compressor suction pressure or a low super-heat condition of the working fluid.
Although prior efforts have been made to provide so-called motorized or power operated expansion valve devices in commercial sizes of air conditioning equipment, such devices and associated controls have not been economically practical, reliable in operation, nor able to provide suitable control over refrigerant fluid flow to control superheat at the compressor inlet for lower capacity (1 to 5 ton) configurations of vapor compression type air conditioning equipment. It is to overcome these deficiencies associated with prior art systems and methods that the present invention has been developed.